Tissue may be destroyed, ablated, or otherwise treated using thermal energy during various therapeutic procedures. Many forms of thermal energy may be imparted to tissue, such as radio frequency electrical energy, microwave electromagnetic energy, laser energy, acoustic energy, or thermal conduction.
In particular, radio frequency ablation (RFA) may be used to treat patients with tissue anomalies, such as liver anomalies and many primary cancers, such as cancers of the stomach, bowel, pancreas, kidney and lung. RFA treatment involves the destroying undesirable cells by generating heat through agitation caused by the application of alternating electrical current (radio frequency energy) through the tissue.
Various electrosurgical instruments have been suggested for this purpose. For example, published PCT application WO 96/29946 discloses electrosurgical probes that include a number of independent wire electrodes that may be extended into tissue from the distal end of a cannula. The electrodes may be energized in a monopolar or bipolar manner to heat and necrose a target tissue region. Such probes have been suggested for treating tumors within organs, such as the liver, kidney, pancreas, stomach, and spleen.
To enhance heating and necrosis, saline may be injected into the target region before delivering electrical energy. Generally, this involves advancing a needle from a syringe into the tissue before or after advancing the electrodes from an electrosurgical probe into the target region. Saline may be delivered from the syringe into the tissue through the needle, and then the electrodes may be energized to deliver RF energy and necrose tissue within the target region. Alternatively, saline may be delivered through a lumen in one or more of the wire electrodes. Saline may increase heating of the tissue, thereby increasing the size of the resulting lesion, as compared to energizing the electrodes without saline.
In existing ablation devices that have fluid delivery capability, the activation of the ablation electrode is controlled by a first control, such as a button, and the delivery of the fluid is controlled by a second control, such as a plunger. However, such device is cumbersome to use because it requires a physician to perform two separates steps, i.e., a first step to operate the ablation device, and a second step to operate the fluid delivery mechanism.
In addition, some existing ablation devices do not have a fluid delivery capability. In such cases, a physician will have to find another device for delivering saline. For example, the physician may use a separate syringe for delivering saline. However, where a separate syringe is used to deliver the saline, the syringe and the ablation device require separate handling by the physician, thereby complicating the procedure.